Temporary vascular filter guide wire

ABSTRACT

A temporary filter is described for use in percutaneous intravascular procedures for the treatment of diseased blood vessels, such as angioplasty or stent placement procedures. The guide wire which is used to direct a catheter (such as a balloon catheter) to a treatment site contains a deployable filter. The guide wire is moveable independently of the catheter and can be used to position the filter at a desired location downstream of the treatment site. The guide wire includes parts moveable with respect to each other and the filter is connected to these parts in such a way that it can be deployed and collapsed by relative movement of the parts.

FIELD OF THE INVENTION

[0001] The invention relates to vascular filters intended to captureembolic particles, by means of filtration, that may arise from thetreatment of diseased blood vessels.

BACKGROUND OF THE INVENTION

[0002] Percutaneous intravascular treatment of diseased blood vessels,such as angioplasty or stent placement procedures, may result in thedislodgment of loose plaque or thrombus which then migrate downstream.Since any such particles may become lodged in other vessels, effectivelypreventing blood from passing into the organ which that vessel supplies,and potentially causing serious end-organ damage which may be difficultor impossible to reverse, effective avoidance of this complication isextremely important.

[0003] One of the early methods of removing residual matter resultingfrom an angioplasty procedure using a balloon catheter involvedmaintaining the balloon in an inflated state while performing theintended intervention on the blood vessel. In this manner, much of thematerial could be removed without an extraneous filtering device.However, the reliability of such a procedure, especially for bloodvessels supplying oxygen to the brain, necessitated substantialimprovement.

[0004] Previous attempts at vascular filters have included a vena cavalfilter, which is permanently deployed in the vena cava via a peripheralvein in order to prevent embolisation of blood clots from the veins ofthe legs to the lungs, thus avoiding potentially serious and lifethreatening pulmonary embolism. The filter typically included aplurality of anchoring legs bent outwardly to form hooks to penetratethe vessel wall and secure the filter permanently in position. Anexample of such a device is disclosed in U.S. Pat. No. 4,619,246.

[0005] While conventional vena caval filters work well for theirintended purposes, they suffer from the disadvantages associated withdamaging the inner vessel wall through the inherent penetrating natureof the hooks, and blockage caused over time as the filter becomesendothelialized with the blood vessel inner wall or as recurrent bloodclots obstruct blood 5 flow through the filter.

[0006] In an effort to resolve the problems with vena caval filters,those skilled in the art have developed temporary filtering mechanismsthat attach to an angioplasty catheter and withdraw from the vasculaturefollowing the procedure. One proposal, disclosed in U.S. Pat. No.4,723,549, discloses a collapsible wire mesh filter disposed around thedistal portion of a wire guided balloon catheter. A filter balloon ispositioned beneath the wire mesh and inflates radially outwardly toexpand the wire mesh when inserted downstream of a stenosed bloodvessel. As the vessel is treated, fine particles dislodged from thestenosis are trapped by the mesh and subsequently removed with thefilter and catheter following the procedure.

[0007] A similar device and method, disclosed in U.S. Pat. No. 4,873,978includes a balloon catheter directed through a vasculature by a guidewire. The catheter mounts a strainer at its distal end that responds toactuation of a separate control wire to open and close a plurality oftines capable of retaining dislodged particles from a treated stenosis.

[0008] The temporary filter devices described above require additionallumens and/or control wires beyond those associated with the catheterguide wire to control the filtering procedure. The extra lines and wirestypically create added complexity for the operator. Moreover, it isoften desirable to adjust the relative spacing between the deployedfilter and the stenosed area due to the potential presence of additionalblood vessels proximate the stenosis. Because the conventional filtersare mounted to the distal ends of the respective catheters, adjustmentsduring the procedure typically cannot be made. Furthermore, the use ofballoon catheters and stent devices involving the same procedure couldnot be achieved with filter protection in place.

[0009] Therefore, a need exists in the art for a temporary vascularfilter which does not require additional control wires and catheterlumens. Moreover, the need exists for such a filter in which adjustmentof the filter with respect to a lesioned vessel area, and allows for theexchange of various types of devices (e.g., balloon catheters, stents,etc.), while maintaining protection against distal emboli. The temporaryvascular filter guide wire of the present invention satisfies theseneeds.

SUMMARY OF THE INVENTION

[0010] The apparatus and method of the present invention minimizes thecomplexity associated with manipulating a vascular filter during anangioplasty or stent placement procedure by incorporating the filter ona catheter guide wire such that the guide wire performs the dualfunctions of guiding the catheter to a stenosed location, and filteringdislodged particles flowing downstream of the treated area. Moreover,because the guide wire operates independently of the catheter, relativespacing between the filter and the lesion location may be easilyaltered, and exchanges of various devices over the wire are possible.

[0011] To realize the advantages described above, the invention, in oneform, comprises a vascular filter guide wire for directing precisionplacement of a catheter or stent proximate a lesion and selectivelyfiltering particulate debris dislodged by treatment. The guide wireincludes an actuating mechanism and an elongated flexible core wirehaving a proximal end mounted to the actuating mechanism and a distalend for insertion through a vasculature to a position downstream of thelesion. A tubular flexible shaft is slidably disposed telescopicallyalong the core wire. The shaft includes a proximal portion affixed tothe actuating mechanism in movable relation to the wire proximal end,and a distal portion disposed inwardly from the core wire distal end forplacement downstream of the lesion. A collapsible strainer coupled tothe shaft distal portion is operable, in response to relativedisplacement between the shaft and the core wire, to radially extendoutwardly within the vasculature so that it can trap particulate matterarising from the treatment of the lesion.

[0012] In another form, the invention comprises a catheter system fortreating a lesion within the vasculature. The catheter system includes acatheter having a lesion treatment device and a vascular filter guidewire for directing the catheter to the lesion. The guide wire includes acollapsible filter for deployment downstream of the catheter to trapparticulate matter dislodged from the lesion during the treatment.

[0013] In yet another form, the invention comprises a method offiltering particulate debris from a vasculature caused by treatment of alesion with a catheter having a lesion treatment portion, the catheterbeing guided to the location of the lesion by a vascular filter guidewire having a core wire, a slidable shaft, and a collapsible filtermounted on the shaft and deployable upon relative displacement betweenthe core wire and the shaft. The method includes the steps of firstguiding the vascular filter guide wire through the vasculature along apredetermined path to a lesion such that the filter is disposeddownstream of the lesion. The next step involves deploying the filterradially outwardly by shifting the shaft relative to the core wire.Then, the catheter is run over the guide wire along the predeterminedpath to position the lesion treatment portion of the catheter proximatethe lesion. The method continues by treating the lesion according to apredetermined procedure then maintaining the filter in a deployedposition until the risk of particulate matter is substantiallyeliminated. The catheter is then withdrawn from the vasculature and thefilter retracted radially inwardly by shifting the shaft back to theoriginal position. The method then concludes with the step of removingthe guide wire from the vasculature.

[0014] One embodiment of the invention comprises a vascular filter forcontrollably expanding within a blood vessel to trap particulate matterloosened from treatment of a lesion. The filter is responsive torelatively shiftable control elements to expand and retract and includesa braid comprising a composite metallic/polymeric material. The materialincludes a plurality of metallic filaments mounted to the respectiveshiftable shaft and core wire to define a support structure and apolymeric mesh interwoven with the metallic filaments to define astrainer.

[0015] Another form of the invention comprises a method of fabricating avascular filter. The method includes the steps of first selecting amandrel having a plurality of consecutively connected forms and weavinga continuous layer of braid over the consecutively connected forms. Themethod proceeds by bonding the braid filaments at spaced apart sectionsbetween respective forms and separating the respective braided forms atthe bonded sections. The forms are then removed from the layer of braid.

[0016] Other features and advantages of the present invention will beapparent from the following detailed description when read inconjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017]FIG. 1 is an enlarged, partial sectional view of a catheter systemof the present invention deployed within a blood vessel;

[0018]FIG. 2 is a partial longitudinal view of a guide wire in aretracted position according to a first embodiment of the presentinvention;

[0019]FIG. 3 is a partial longitudinal sectional view along line 3-3 ofFIG. 2;

[0020]FIG. 4 is a partial longitudinal sectional view similar to FIG. 3but in a deployed orientation;

[0021]FIG. 5 is an enlarged view of detail 5-5;

[0022]FIG. 6 is a longitudinal view of a filter construction accordingto an alternative embodiment of the present invention;

[0023]FIG. 7 is a longitudinal view of a filter construction accordingto yet another embodiment of the present invention;

[0024]FIG. 8 is a mandrel system for use in the method of the presentinvention;

[0025]FIG. 9 is a block diagram illustrating steps in preparing themandrel of FIG. 8;

[0026]FIG. 10 is a block diagram illustrating steps in fabricating thefilter of the present invention;

[0027]FIG. 11a-11 g are views of various stages of constructioncorresponding to the steps of FIG. 10;

[0028]FIG. 12 is a partial longitudinal sectional view of a guide wirein a retracted state according to a second embodiment of the presentinvention;

[0029]FIG. 13 is a partial view of the guide wire of FIG. 12 in anextended state;

[0030]FIG. 14 is an axial view along line 14-14 of FIG. 13;

[0031]FIG. 15 is an axial view similar to FIG. 14 and showing analternative strut arrangement; and

[0032]FIG. 16 is an axial view similar to FIG. 14 and showing analternative strut arrangement.

DETAILED DESCRIPTION OF THE INVENTION

[0033] With reference to FIG. 1, percutaneous angioplasty or stentplacement techniques enable operators to minimize trauma oftenassociated with more invasive surgical techniques.

[0034] This is possible through the use of a thin catheter 20 thatadvances through the vascular system to a predetermined blood vessel 22having a lesion such as a stenosis 24 blocking the flow of bloodtherethrough. Typically, the catheter includes a lesion treatment devicesuch as a balloon 26 or stent (not shown) for positioning coaxiallywithin the lesion. Once positioned, the balloon or stent radiallyexpands, as shown at 28, to exert a radially outwardly directed forceagainst the material and initiate dilation thereof.

[0035] In order to reach the lesioned area, however, the catheter mustbe able to follow a trackable path defined by a catheter guide wire. Inaccordance with a first embodiment of the present invention, a catheterguide wire, generally designated 30, provides a trackable path for acatheter and includes a distally disposed collapsible filter 50 to trapparticulate matter dislodged by the catheter 20 during treatment of thestenosis.

[0036] Referring now to FIGS. 2 through 5, the guide wire 30 includes aproximal section 32 comprising a solid core wire 34 having a wave-shapedproximal end 36 (FIG. 2). A tubular shaft 38 is coaxially disposedaround the core wire and includes an outer diameter equal to the nominalsize of the guide wire.

[0037] The inner diameter of the tube is sized to form a friction fitwith the core wire proximal end when slid thereover during insertion andremoval of the guide wire. The shaft functions to deploy and retract thefilter device, and to guide and support the catheter 20, and to smoothlytransmit rotation from the proximal section 32 to an intermediatesection 40. Preferably, the shaft comprises a polyimide tube orhypotube. In some applications, where relatively long lengths arerequired, an extension (not shown) may be attached to the proximalsection to increase the length up to three meters.

[0038] The intermediate section 40 extends axially from the proximalsection 32 and generally comprises an extension of the shaft 38 tocoaxially surround the core wire 34. The core wire is formed distallywith a primary tapered portion 42 defining an annular shoulder 44 formounting a coiled spring 46.

[0039] With further reference to FIGS. 2 through 5, the filter 50comprises a braided basket 52 having respective inner and outer braidlayers 54 and 56 (FIG. 5) that, in one embodiment, serve as supports fora fine filter mesh 58. The supports expand the basket radially outwardlywith the filter axial ends compressed inwardly, and radially retract thebasket with the ends tensioned outwardly. The fine mesh 58 (FIG. 5) isinterposed between the inner and outer supports along a distal-halfportion 60 of the basket to prevent particulate matter from flowingthrough the blood vessel downstream of the treated stenosis. It iscontemplated that the size of the pores of mesh 58 may be in the rangeof 40 to 500 microns. The meshed distal-half of the filter forms acollection cavity 62 for the material such that when retracted, thematerial is prevented from escaping the filter.

[0040] The proximal end of the filter basket is bonded (e.g. adhesivelyor by soldering) to the shaft 38 which may be inserted between braidlayers 54 and 56.

[0041] The distal extremity 57 of basket abuts a flexible coil spring 66that coaxially surrounds the tip of the core wire 34. The guide wiredistal tip is tapered and terminates in a hemispherically shaped tip 72which is also bonded (e.g. by soldering) to the tip. The guide wiredistal tip may be preformed into a “J” configuration (not shown) to aidin advancing the guide wire 30 through the vasculature.

[0042] With particular reference to FIG. 6, the preferred embodiment offilter 50 according to the present invention includes a braid comprisinga composite metallic/polymeric material, eliminating the necessity of aseparate mesh layer. In such an embodiment, a plurality of metallicfilaments 82 provide structural support to the assembly for deployingand collapsing the filter. Polymeric filaments 84 are located on thedistal half of the braid only, to provide a filtration cone 86. The dualmaterials, braided simultaneously, provide a pic density which willresult in filtration spacing of approximately 40 to 500 microns forfiltration, at a metal to polymeric ratio of approximately 1:4.

[0043] In yet another embodiment of a filter according to the presentinvention, generally designated 90 and illustrated in FIG. 7, thefiltering medium is wrapped in a cylinder 92 with a closed distal end 94and a flared proximal end 95. Flaring of the proximal end may beeffected by applying heat and pressure to the material therebyincreasing the surface area and causing the material to bow radiallyoutwardly. The cylinder is formed with longitudinal pleats (not shown)that are more flexible and collapsible than a straight coneconfiguration.

[0044] Referring now to FIGS. 8 and 9, fabrication of the filter 50 maybe performed in accordance with a series of process steps as describedbelow. Initially, a mandrel 96 (FIG. 8) with a series of molded forms 97and 98 is prepared by selecting a mandrel of appropriate length, at step100 (FIG. 9), and providing a plurality of crimps 101 (FIG. 8) on themandrel at intervals of approximately two to three inches, at step 102.The process proceeds by placing molds over the crimps, at step 104,filling the molds with a dissolvable compound, at step 106, curing thecompound, at step 108, and removing the molds, at step 110. Suitablematerials for molding include water soluble plastics such aspolyethylene oxide, chemical soluble plastics such as styrene or PVC,and other water soluble materials such as sugar cubes, or gypsum basedcompounds. Molded forms may be continuously fabricated along the lengthof the crimped mandrel sections to maximize production efficiency.Another suitable method envisioned is to individually form the molds andbond to straight mandrels.

[0045] Referring now to FIGS. 10 and 11a-g, following preparation of themandrel 96, the mandrel itself is selected for the method of fabricatingthe filters, at step 112. The method progresses by selecting a braider,at step 114, and braiding the inner layer 54 (FIG. 11a), at step 116,over the mandrel form system. Because of the convenient seriallyconnected system of forms on the mandrel, the braider progressivelyweaves a continuous layer of braid over the consecutively connectedforms. After the braid is applied, the mandrel is removed from thebraider, at step 118, so that a curable epoxy may be applied to definean adhesive joint 119 (FIG. 11b) along spaced apart sections of thebraid between forms. This step bonds braid filaments together, at step120, so that subsequent separation of the forms minimizes deformation ofthe braid.

[0046] A center section 121 (FIG. 11c) of each braid is then cut, atstep 122, and a prefabricated filter 123 (FIG. 11d) installed over oneside of each form, at step 124. The individual segments are thenreconnected, at step 126, by splicing a section of heat shrink tubing127 (FIG. 11e) over each severed joint.

[0047] After the segments are re-connected, the mandrel assembly is thenre-installed into the braider for braiding of the outer basket 56 (FIG.11f), at step 128. Following braiding, the mandrel is removed from thebraider, at step 130, with the braid filaments bonded together to form ajoint 131 (FIG. 11g), at step 132. The mandrel is then cut atapproximately one millimeter on the outside end of the adhesive, at step134. At this point, the molded form may be dissolved by an appropriatesolvent, at step 136, and the mandrel removed, at step 138. Lastly, apolyimide sleeve is bonded, at step 140, to the end opposite the filter.

[0048] The alternative filter embodiment 80 may be fabricated similar tothe procedure above with only minor variations. Conveniently, because ofthe composite nature and relatively high pic density of themetallic/polymeric braid, only one braiding step is required. After thefinal braid, the polymeric strands at the proximal end are mechanicallyor thermally cut away, and the filaments fused at the large diameter ofthe formed cone to form the collection cavity and to allow for greaterblood flow.

[0049] In operation, the guide wire 30 may be advanced through avascular system in any conventional manner to establish a path for thecatheter to track over. Generally, as shown in FIG. 1, the guide wire isinserted through the lesion and disposed downstream of the lesion 24 avariably selected distance. The distance selected by the operator may beconveniently adjusted merely by further advancing or slightlywithdrawing the guide wire. This provides the highly desirablecapability of enabling the operator to independently adjust the selecteddistance to preclude the possibility of embolic material progressingthrough a branch path between the lesion and the filter. The catheter 20is then inserted along the guide wire to access the treatment area.Typically, image scanning techniques aid in the exact positioning of thecatheter relative to the lesion such that the lesion treatment devicewill have maximum effectiveness.

[0050] The filter may then be deployed by actuating an actuatingmechanism (not shown) coupled to the core wire 34 for axially moving theshaft 38 relative to the core wire. As the shaft advances axially alongthe core wire in the distal direction, the filter basket 52, having itsdistal end 57 attached to the fixed core wire and its proximal endconnected to the shaft, compresses axially and expands radiallyoutwardly against the inner walls of the blood vessel. In its expandedstate, the filter 50 collects any plaque that may have loosened andbecome dislodged from the treated area.

[0051] Once the treatment concludes, and the catheter is withdrawn fromthe body, the filter is retracted radially inwardly by shifting theshaft back to its original position. As the filter retracts, thecollection cavity 62 traps any material strained against the filterlayer. The guide wire itself is then carefully withdrawn from thevasculature.

[0052] Referring now to FIGS. 12 through 16, a temporary filter guidewire according to a further embodiment of the present invention isshown, and generally designated 200. The guide wire generally includes aproximal end 202 having an actuating mechanism 208, an intermediateportion 220 including a housed collapsible filter element 222, and aflexible distal end 240.

[0053] With particular reference to FIG. 12, the proximal end 202includes a solid stainless steel core wire 204 having a diameter, forexample, of approximately 0.0075 inches and slidably confined coaxiallyby an elongated shaft 206. The shaft may include, for example, an innerdiameter of approximately 0.010 inches and an outer diameter ofapproximately 0.014 inches. The proximal tip of the core wire nestswithin the handle mechanism 208 that includes a rotatable handle element209 having a formed central blind bore 210 and a threaded hollow shank212. A fixed threaded base 214 having a throughbore 216 receives theproximal portion of the shaft 206 and rotatably engages the handleelement to define the actuating mechanism.

[0054] Referring now to FIGS. 12 and 13, the core wire 204 and the shaft206 extend longitudinally to define the intermediate portion 220 of theguide wire. The filter element 222 is mounted to the intermediateportion and includes an intermediate quad filar spring 224 ofapproximately 0.002 inch diameter wire that extends approximately threeto seven centimeters from the end of the shaft, depending on theapplication. The respective ends of four wires comprising the quadspring are unwound, straightened, and outwardly biased approximatelyforty-five degrees from the spring axis at spaced apart radial locationsto define a plurality of umbrella shaped filter struts 226. These strutsform the support structure for the filter. As shown in FIGS. 14, 15, and16, the strut spacing may conveniently take on a variety ofconfigurations depending on the particular application desired. Lashedto the struts is a fine wire mesh 228 of approximately 0.001 inchesthink within 40 to 500 micron pores for straining particulate matterfrom the bloodstream.

[0055] Further referring to FIG. 12, the radial exterior of the distalportion of the core wire 204 carries a bonded housing or pod 230 havingan axially open mouth 232 slightly larger in diameter than the diameterof the filter in a closed configuration. The mouth opens into a cavitysufficiently sized to fully enclose the filter during insertion orwithdrawal of the guide wire. The pod would also have a rounded inwardedge at its proximal opening so as to envelop the filter when retractedand prevent unintentional engagement of a stent or catheter uponwithdrawal. The pod may be fabricated out of a spring material wound inthe opposing direction as the spiral struts to improve the sliding ofthe two surfaces. Other options include a lubricious plastic such aspolyethylene.

[0056] The distal end 240 of the guide wire 200 comprises an extensionof the core wire 204 from a bonded distal joint and surrounded by adistal spring member 242 that bonds to and projects outwardly from thedistal side of the filter housing 230. The distal end terminates in atip 244 that typically takes on a pre-formed “J” shape (not shown) forsteering purposes through the vascular system.

[0057] Operation of the second embodiment proceeds in much the same wayas that of the first embodiment, with the guide wire 200 first directedthrough the vasculature, followed by tracking with a treating catheter.Like the first embodiment, the guide wire 200 is advantageouslyadjustable in the blood vessel independent of the catheter, allowing avariable selected distance between the location of the stenosis and thefilter.

[0058] However, the way in which the filter 222 expands and retractsdiffers somewhat from the previously described embodiment.

[0059] With the handle mechanism 208 in a normally open configuration,the operator turns the rotatable element 209 to incrementally drive thecore wire 104 axially with respect to the shaft 206. The relative axialdisplacement of the core wire causes the filter housing 230 to becomedisengaged from the filter struts 226. Because of the spring biasednature of the filter struts 226, as the filter exits the housing, thestruts expand radially outwardly against the blood vessel wall such thatthe wire mesh spans the vessel diameter. In its extended state, thefilter allows bloodflow to continue through the vessel while dislodgedmaterial becomes entrapped in the wire mesh for collection in thecavity.

[0060] Once the lesion treatment procedure is complete, and thenecessity for filtering has completely diminished, the handle mechanismis actuated to pull the core wire back to its original position. Thisactivity causes the housing mouth to re-engage the filter struts andurge the struts radially inwardly as the housing encloses the filter.With the filter fully retracted, the streamlined guide wire may beeasily and safely withdrawn from the body.

[0061] Those skilled in the art will appreciate the many benefits andadvantages afforded the present invention. Of relative importance is thefeature that avoids any additional control wires, beyond the guide wireitself, in order to expand and retract the filter. Not only does thisminimize the number of components necessary to practice the invention,but the angioplasty procedure itself is made safer for the patient.

[0062] Additionally, the present invention provides the capability ofadjusting the distance between the filter and the catheter lesiontreatment device in vivo, eliminating the need to withdraw the guidewire or catheter for distance adjustment should the relative spacing beinadequate.

[0063] The filter itself, in one embodiment, provides substantialmanufacturability benefits by requiring only a single braiding step.Consequently, braiding additional filter layers adding to the device'scomplexity are eliminated. By minimizing the process steps required tofabricate the filter, costs involved in manufacture are greatly reduced.

[0064] Moreover, the method of fabricating filters according a to thepresent invention offers added efficiencies in manufacture due to theproduction line processing scheme.

[0065] Employing such a scheme serves to dramatically improve thethroughput rate of filters to minimize overall costs.

[0066] While the invention has been particularly shown and describedwith reference to the preferred embodiments thereof, it will beunderstood by those skilled in the art that various changes in form anddetail may be made therein without departing from the spirit and scopeof the invention.

[0067] For example, the invention may be used in any intravasculartreatment utilizing a guide wire where the possibility of looseningemboli may occur. Although the description herein illustratesangioplasty and stent placement procedures as significant applications,it should be understood that the present invention is in no way limitedonly to those environments.

What is claimed is:
 1. A vascular filter guide wire for directingplacement of a catheter with respect to a blood vessel lesion andfiltering particulate matter dislodged by treatment of said vessel, saidguide wire including: an elongated flexible core wire having a proximalend and a distal end for insertion and steerage through a patient'svasculature to a position downstream of said lesion; a tubular flexibleshaft slidably disposed along said core wire, said shaft including aproximal portion and a distal portion disposed proximally of said corewire distal end for placement downstream of said lesion; and acollapsible filter coupled at its proximal end to said distal portion ofsaid shaft and at its distal end to said core wire, said filter operablein response to the relative is displacement between said shaft and saidcore wire to radially extend outwardly within said vasculature and trapparticulate matter arising from the treatment of said lesion.
 2. Avascular filter guide wire according to claim 1 and further including: alocking mechanism to maintain said filter in a deployed position forparticulate filtration during lesion treatment.
 3. A vascular filterguide wire according to claim 1 wherein: said core wire includes afilter housing for confining said filter in a closed configuration.
 4. Avascular filter guide wire according to claim 3 wherein: said housing isformed in a frusto-conical configuration and axially disposed on saidcore wire, said housing including an oversized-in-diameter mouth openingaxially outwardly from said wire distal end, and a reduced-in-diametercollar radially fixed to said core wire proximate said distal end.
 5. Avascular filter guide wire according to claim 3 wherein said strainer isformed to collapsibly engage said housing in a closed state andincluding: a plurality of radially spaced apart support struts defininga cage, said struts collapsibly hinged at one end along a common radialpath on said shaft and interconnected through a woven peripheral mesh;and a biasing element interposed concentrically between said struts andsaid shaft to bias said struts radially outwardly in an open state.
 6. Avascular filter guide wire according to claim 5 wherein: said spacedapart struts are disposed radially equidistant.
 7. A vascular filterguide wire according to claim 5 wherein: said spaced apart struts aredisposed in a spiral relationship.
 8. A vascular filter guide wireaccording to claim 5 wherein: said struts are formed of a high elasticmaterial.
 9. A vascular filter guide wire according to claim 5 wherein:said woven mesh comprises a polymeric material.
 10. A vascular filterguide wire according to claim 5 wherein: said woven mesh density is inthe range 40 to 500 micrometers.
 11. A vascular filter guide wireaccording to claim 5 wherein: said biasing element comprises a quadfilar spring.
 12. A vascular filter guide wire according to claim 1,further including a deployment/retraction mechanism including: aremovable base formed with a threaded passage for confining the proximalportion of said shaft; and a manually rotatable control element, saidcontrol element formed with a threaded hollow shank and mounted to theproximal end of said wire, said control element operable to threadablyengage said passage and incrementally urge relative axial displacementbetween said shaft and said wire to extend and retract said filter. 13.A vascular filter guide wire according to claim 1 wherein said filterincludes: a cylindrical support cage having a closed distal end and aflared proximal end, said distal end fixed to the distal extremity ofsaid shaft, and said proximal end extending axially and mounted to saidcore wire distal end; and a continuous woven mesh having a plurality oflongitudinal pleats and disposed within said support cage for strainingparticulate matter.
 14. A vascular filter guide wire according to claim13 wherein: said filter is formed with oppositely disposed cone-shapedends to define said front and back halves.
 15. A vascular filter guidewire according to claim 14 wherein said woven mesh is mounted to saidcage back half.
 16. A vascular filter guide wire according to claim 13wherein: said woven mesh comprises a material from the group includingstainless steel and nickel-titanium alloy.
 17. A vascular filter guidewire according to claim 13 wherein: said wire mesh density is in therange 40 to 500 micrometers.
 18. A vascular filter guide wire accordingto claim 1 wherein said filter includes: a braid comprising a compositemetallic/polymeric material, said material including a plurality ofmetallic filaments mounted to said respective shiftable shaft and corewire to define a support structure and a polymeric mesh interwoven withsaid metallic filaments to define a strainer.
 19. A vascular filterguide wire according to claim 18 wherein: a said metallic filaments haverespective common proximal and distal halves; and said polymeric mesh isinterwoven in said distal half of said metallic filaments.
 20. Avascular filter guide wire according to claim 18 wherein: said metallicand polymeric filaments are woven at a ratio of approximately 1:4.
 21. Avascular filter guide wire for directing precision placement of acatheter with respect to a lesion and filtering particulate matterdislodged by treatment of said lesion, said guide wire including: anactuating mechanism; an elongated flexible core wire having a proximalend attached to said actuating mechanism and a distal end for insertionand steerage through a patient's vasculature to a position downstream ofsaid lesion; a tubular flexible shaft slidably disposed along said corewire, said shaft including a proximal portion affixed to said actuatingmechanism in movable relation to said wire, and a distal portiondisposed inwardly from the distal end of said core wire for placementdownstream of said lesion; a locking mechanism to maintain said filterin an extended position during lesion treatment; and a collapsiblefilter coupled to said shaft distal portion, said filter including acollapsible support cage having respective front and back halves forslidably extending and retracting axially along said wire, said cagehaving a first end fixed to the distal extremity of said shaft, and anopposite end mounted to said core wire distal end, said strainer furtherincluding a continuous woven mesh disposed within said support cage forstraining particulate matter and operable, in response to manualmanipulation of said actuating mechanism to effect relative displacementbetween said shaft and said core wire, to radially extend outwardlywithin said vasculature and trap particulate matter arising from thetreatment of said lesion.
 22. A catheter system for treating a bloodvessel lesion within a vasculature, said catheter system including: acatheter having a lesion treatment device; and a vascular filter guidewire for directing said balloon catheter to said lesion, said guide wireincluding a collapsible filter for manual deployment downstream of saidballoon catheter to trap particulate matter arising from the treatmentof said lesion.
 23. A catheter system according to claim 22 wherein saidvascular filter guide wire includes: an elongated flexible core wirehaving a proximal end and a distal end for insertion and steeragethrough a patient's vasculature to a position downstream of said lesion;a tubular flexible shaft slidably disposed along said core wire, saidshaft including a proximal portion and a distal portion disposedinwardly from said core wire distal end for placement downstream of saidlesion; and a collapsible filter coupled at one end to said shaft and atits other end to said core wire, said filter operable in response torelative displacement between said shaft and said core wire, to radiallyextend outwardly within said vasculature and trap particulate matterarising from the treatment of said lesion.
 24. A method of filteringparticulate debris from a vasculature caused by treatment of a lesionwith a lesion treatment device, said catheter guided to the location ofsaid lesion by a vascular filter guide wire having a core wire, aslidable shaft, and a manually collapsible filter mounted on the shaftand deployable upon relative displacement between said core wire andsaid shaft, said method including the steps of: guiding said vascularfilter guide wire through said vasculature along a predetermined path toa lesion such that said filter is disposed downstream of said lesion;deploying said filter radially outwardly by shifting said shaft relativeto said core wire; running said catheter over said guide wire along saidpredetermined path to position said lesion treatment device proximatesaid lesion; treating said lesion according to a predeterminedprocedure; maintaining said filter in a deployed position to trapparticulate matter dislodged during said lesion treatment and preventsaid matter from progressing downstream; withdrawing said catheter fromsaid vasculature; retracting said filter radially inwardly by shiftingsaid shaft back to said original position; and removing said guide wirefrom said vasculature.
 25. A vascular filter for controllably expandingwithin a blood vessel to trap particulate matter loosened from a lesion,said filter responsive to relatively shiftable control elements toexpand and retract, said filter including: a braid comprising acomposite metallic/polymeric material, said material including aplurality of metallic filaments mounted to said respective shiftableshaft and core wire to define a support structure, and a polymeric meshinterwoven with said metallic filaments to define a strainer.
 26. Avascular filter guide wire according to claim 25 wherein: said metallicfilaments have respective common proximal and distal halves; and saidpolymeric mesh is interwoven in said distal half of said metallicfilaments.
 27. A vascular filter guide wire according to claim 25wherein: said metallic and polymeric filaments are woven at a ratio ofapproximately 1:4.
 28. A method of fabricating a vascular filter, saidmethod including the steps of: selecting a mandrel having a plurality ofconsecutively connected forms; weaving a continuous layer of braid oversaid consecutively connected forms; bonding said braid filaments atspaced apart sections between respective forms; separating saidrespective braided forms at said bonded sections; and removing saidforms from said layer of braid.
 29. A method of fabricating a vascularfilter according to claim 28 wherein said step of weaving includes:forming a layer of braid over the proximal and distal halves of eachform with a composite metallic/polymeric material to having a picdensity sufficient to strain particulate matter.
 30. A method offabricating a vascular filter according to claim 29 and furtherincluding the step of: cutting said polymeric filaments from saidproximal halves of each form; and fusing the ends of said cut filamentsto form a collection cavity around each form.
 31. A method offabricating a vascular filter according to claim 28 wherein after saidbonding step, said method further includes the steps of: installing afilter layer over each form; weaving a second continuous layer of braidhaving a plurality of second braid filaments over said installedfilters; and bonding said second braid filaments at said spaced apartsections.
 32. A method of fabricating a vascular filter according toclaim 28 wherein said forms are molded from a dissolvable material, saidstep of removing including: dissolving said forms by an appropriatesolvent.